Biological Cells as State Machines

For robot builders hoping to one day achieve a robot with a complexity
equivalent to a
single-celled animal, the bar has just been raised. A National
Science Foundation news release describes new research into how
biological cells store information about a cell's state and operation
using biochemical switches. Naren Ramakrishnan, a professor of
computer science at Virginia Tech, and Upinder S. Bhalla at the National
Centre for Biological Sciences in India tried a new approach by looking
at cells from the standpoint of an electrical engineer. Using a
supercomputer, the researchers located thousands of chemical reactions
that form bistable circuits capable of storing binary information. They
also discovered the switches are related to each other, with more
advanced switches identical to simpler switches but with one or
two additional chemical reactions, suggesting possible clues to their
evolutionary development within the cell (the diagram above shows how
the newly discovered switches are related). The switches also form the
equivalent of an electronic circuit. The next step is to look for other
functional units such as oscillator and amplifiers, until it's possible to
understand a complete "wiring diagram" of cells. To read all the
technical details of the research, see the paper Memory
Switches in Chemical Reaction Space (PDF format).